A common hazard of liquids, especially water for drinking, household, medical, and industrial uses, is contamination by harmful microorganisms such as bacteria, viruses, cysts, and the like. Gastrointestinal disorders and illnesses are caused by water contaminated by microorganisms. The microorganisms present in liquid systems can come from a variety of sources. The safety and potability of certain water supplies, using source liquid from wells, springs, water pumps, septic tanks, reservoirs, water treatment devices, water lines, and the like, is a serious health and safety concern.
Bacteria and microorganisms present in water unfortunately cannot be seen, tasted, smelled, or easily detected, and many health-related symptoms are caused by bacteria and microorganisms that are not immediately visible. Water contamination is generally identified by one or a panel of laboratory tests. However, testing a water supply for a specific disease-causing organism can be quite expensive. Also, handling and intentionally culturing disease producing organisms requires special training and equipment.
Boiling of water is known to be an extremely effective means to eliminate bacterial populations and ensure that the water is safe. Water that has been boiled continuously for at least 15 minutes will be substantially free from nearly all bacteria. However, this method of eliminating bacteria and microorganisms in water is not always practical and almost impossible for treatment of large volumes of water. It is also common nowadays for a person to purchase bottled water for personal consumption or use an in-home water filtration system, but these alternatives to tap water again can be costly and can become cumbersome.
Most household water can be disinfected continuously by chlorination, distillation, ultraviolet light, or ozonation. Chlorination is widely used to disinfect water because it destroys bacteria within a reasonable contact time and provides long term protection. Chlorine, readily available at a low cost, is easy to handle and is also effective in controlling algae. However, chlorine has its limitations. Organic matter as well as iron and manganese can interfere with the action of chlorine. Low levels of chlorine normally used to disinfect water are not an effective treatment for some parasites and microorganisms, and even low levels of chlorine concentrations can result in objectionable tastes and odors. Chlorinators, although simple to operate, require regular refilling with chemicals. Chlorine bleach can be added to water for sanitation purposes and sanitizing a contaminated well, a spring, a swimming pool, or a plumbing system, for example, can be accomplished by shock chlorination. However, shock chlorination introduces high levels of chlorine in the water and high levels of chlorine can be toxic and can be irritable to human organs and skin and Therefore, while water treated by chlorine may be suitable for some applications and settings, it may not be suitable or safe for human consumption. In addition, water treatment equipment, such as water softeners, iron filters, or sand filters, can be damaged by strong chlorine solutions.
The heat necessary to provide water distillation is very effective in killing disease-causing microorganisms. One of the benefits of distillation is that the process uses no chemicals. Distillation, however, takes longer to produce the processed water than some other methods. Also, the distillation units can be expensive to operate, and the long period of storing distilled water can affect its quality.
Exposure to ultraviolet light is also a very effective methodology for disinfecting water. This method also disinfects water without adding chemicals. Ultraviolet light disinfection units do not create any new chemical complexes, do not change the taste or odor of the water, and do not remove beneficial minerals from the water. However, ultraviolet light is only effective against some bacteria. It is not effective against some viruses and parasites such as giardia. In addition, there is no simple test to determine whether disinfection by ultraviolet light provides a proper level of disinfection. Further, ultraviolet light devices are most effective when water is clear and such devices allow the light to easily pass through. Thus, to ensure proper disinfection, ultraviolet light device often need to be combined with other treatment devices such as mechanical filters, activated carbon filters, water softeners, and reverse osmosis systems to provide complete water quality solutions.
Ozonation uses ozone, which is a more powerful disinfectant than chlorine. Ozone produces no tastes or odors in the water. However, as a gas, ozone is unstable and has a very short life so it must be generated at the point of use. This is impractical and cumbersome.
U.S. Pat. No. 5,591,317 discloses an electrostatic-field generator for use in water treatment that consists of a vitrified ceramic tube of unibody construction having a single open end adapted to receive a high-voltage power cable through an insulated cap. The interior surface of the ceramic tube is lined with a layer of conductive material electrically connected to the power cable, thereby providing a relatively-large conductive surface in intimate contact with the dielectric surface of the ceramic tube. In operation, the device is immersed in a body of water connected to ground and the power cable is energized with a high DC voltage, thereby creating an electrostatic field across the dielectric of the tube's ceramic and across the body of water. Because of the difference in the dielectric coefficients of the materials, the majority of the applied potential is measured across the water, thus providing the desired electrostatic effect on its particulate components.
U.S. Pat. No. 5,817,224 discloses a method for enhancing the efficiency of a solid-liquid separation process by using an electrostatic-field generator that utilizes a vitrified ceramic tube of unibody construction having a single open end adapted to receive a high-voltage power cable through an insulated cap. The interior surface of the ceramic tube is lined with a layer of conductive material electrically connected to the power cable, thereby providing a relatively-large conductive surface in intimate contact with the dielectric surface of the ceramic tube. The device is used in connection with conventional chemical additives for separating suspended solids from water to reduce chemical consumption and improve operating efficiency. The device is immersed in the water carrying suspended particles upstream of the treatment with chemical agents and is energized with a high DC voltage, thereby creating an electrostatic field across the dielectric of the tube's ceramic and across the body of water. The charge on the surface of particles to be separated by physical aggregation is altered by the electrostatic field so generated and is manipulated so as to produce enhanced performance by the chemicals used in the conventional process downstream.
U.S. Pat. No. 4,772,369 discloses a process and an apparatus for treating water which comprises decomposing the minerals dissolved in the water into cations comprising ferromagnetic, paramagnetic and residual particles, and desegregating the cations and anions by utilizing ferromagnetic particles as a temporary mobile anode facing a strong cathode and paramagnetic particles as a weak cathode. The desegregated minerals form a dielectric layer on the strong cathode, which is extracted.
U.S. Pat. No. 6,679,988 discloses a water purification system for production of USP purified water and/or USP water for injection including a backwashable, chlorine tolerant microfilter or ultrafilter for initial filtration of the feed water. The filtrate from the filter is provided to a dechlorinator prior to being subjected to an optional, reverse osmosis membrane unit and then to a still which discharges purified water at USP standards for purified water or water for injection.
U.S. Pat. No. 6,689,270 discloses a water treatment apparatus reducing hard water deposits in a conduit. Water having dissolved salts therein causing scaling is treated by flowing through a passage in an elongate tubular member. The tubular member has a first metal inside surface exposed to the water. A second metal surface is positioned therein and the two surfaces have areas of 1:1 up to about 125% with the second metal being different from the first metal. The metal surfaces are electrically insulated from each other so that current flow between the two is through the water.
U.S. Pat. No. 6,849,178 discloses an apparatus for water treatment by means of an electrical field is provided with an anode and a cathode in at least one treatment chamber through which the water to be treated passes. The apparatus is characterized in that the at least one treatment chamber forms a prismatic space with an elongated cross section, the anode and the cathode are formed by pairs of parallel, stick-shaped electrodes which extend spaced apart into said space and a voltage is applicable between the electrodes. One end of the at least one treatment chamber is connected to a water inlet and the other end of the at least one treatment chamber is connected to a water outlet, whereby a waterflow from one electrode to the other is generated, which is substantially transverse to the longitudinal axes of the electrodes.